Hi Mark
Thanks for the quick reply.
That shinny box tubing was magnetic and it seemed to weld real clean with C25/ER70S-6. So, I don't know ~~~~~~~ sure looked like SS to me but IDK. ???
I'm heading back to the metal supply shop tomorrow to trade in my pile for a new pile.

I'll ask them about that box tubing. I'll also try upping the gun speed a little bit to perhaps reduce the convex bead issue a little bit. I also have some unplated 3/8" and 1/2" REBAR so I may try some butt welds on that stuff.
When everything was running nice the weld process had a really sweet sizzle sound!

regards
JohnG